Editing Islamic philosophy (section)

===End of the classical period===
By the 12th century, ''Kalam'', attacked by both the philosophers and the orthodox, perished for lack of champions. At the same time, however, ''Falsafa'' came under serious critical scrutiny. The most devastating attack came from [[Al-Ghazali]], whose work ''Tahafut al-Falasifa'' (''[[The Incoherence of the Philosophers]]'') attacked the main arguments of the Peripatetic School.<ref>Leaman, 25, 27.  "In this book [''Intentions of the philosophers''] he seeks to set out clearly the views of his opponents before demolishing them, in the subsequent ''Incoherence of the philosophers''."</ref>

Averroes, [[Maimonides]]' contemporary, was one of the last of the Islamic Peripatetics and set out to defend the views of the ''Falsafa'' against al-Ghazali's criticism. The theories of Ibn Rushd do not differ fundamentally from those of [[Ibn Bajjah]] and [[Ibn Tufail]], who only follow the teachings of Avicenna and Al-Farabi. Like all Islamic Peripatetics, Averroes admits the hypothesis of the intelligence of the spheres and the hypothesis of universal emanation, through which motion is communicated from place to place to all parts of the universe as far as the supreme world—hypotheses which, in the mind of the Arabic philosophers, did away with the dualism involved in Aristotle's doctrine of pure energy and eternal matter.

But while Al-Farabi, Avicenna, and other Persian and Muslim philosophers hurried, so to speak, over subjects that trenched on traditional beliefs, Ibn Rushd delighted in dwelling upon them with full particularity and stress. Thus he says, "Not only is matter eternal, but form is potentially inherent in matter; otherwise, it were a creation ''ex nihilo''" (Munk, "Mélanges," p.&nbsp;444). According to this theory, therefore, the existence of this world is not only a possibility, as Avicenna declared, but also a necessity.